Composite consisting of a coated polycarbonate and a polymer

ABSTRACT

A composite plastic structure is described. The composite structure includes: (a) a shaped polycarbonate article having an edge region, the edge region having an adhesion-promoting geometric feature therein; (b) a coating applied to the surface of the shaped polycarbonate article; and (c) a polymer that is injection-molded or cast over the edge region of the shaped polycarbonate article. The polymer (c) envelopes the adhesion-promoting geometric feature of the shaped polycarbonate article (a). The envelopment of the adhesion-promoting geometric feature by the polymer (c) provides a structurally firm connection between the shaped polycarbonate article (a) and the polymer (c). Also described is a method of preparing the composite structure, and composite structures according to the present invention, such as picture frames, slide frames, windows having a seal or frame, and a glazing for a motor vehicle.

FIELD OF THE INVENTION

The present invention relates to a composite structure comprising ashaped polycarbonate article, the surface of which is coated and whichhas an adhesion-promoting geometric feature in the edge region, and apolymer; the production of the composite structure; the use thereof forthe production of products; and products produced therefrom.

BACKGROUND OF THE INVENTION

The replacement of glass by polycarbonate has progressed ever further,especially in areas where glass is a disadvantage because of its weightand/or because of its susceptibility to fracture.

Polycarbonate, which can be employed as a glass substitute, must becoated so that it is both scratch-resistant and resistant to otherenvironmental influences. However, such coating of the polycarbonate asa rule has the result that the polycarbonate will not undergo chemicalor physical bonding to other polymers, so that a composite structure,wherein another polymer is firmly adhered to the coated polycarbonate,is generally not possible without the aid of connecting means, such ase.g. screws.

SUMMARY OF THE INVENTION

The object of the present invention is therefore to provide a compositestructure comprising a shaped polycarbonate article, the surface ofwhich is coated, and a polymer, wherein the composite has a firmstructure without the need for connecting means, such as e.g. screws; aprocess for the production of the composite according to the invention;and products which are produced therefrom.

The object according to the invention is achieved by a compositestructure comprising a shaped polycarbonate article, the surface ofwhich is coated and which has an adhesion-promoting geometric feature inthe edge region, and a polymer, which is obtainable byinjection-moulding or casting the polymer around the shaped article inthe edge region; a process for the production of the composite accordingto the invention by injection-moulding or casting material around theshaped article of polycarbonate in the edge region; the use thereof forthe production of products; and the products thus obtainable.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a representative depiction of a composite structure 16according to the present invention which includes a polycarbonate film11 with bores 20 in the edge region 23, and a partially cut-away polymerelement 35;

FIG. 2 is a representative depiction of a polycarbonate film 12 havingrecesses 26 in the edge region 6;

FIG. 3 is a representative sectional view of a polycarbonate film 1having indentations or scallops in the edge region 29; and

FIG. 4 is a representative depiction of a polycarbonate film 14 havinghalf-stamps 32 in the edge region 38.

DETAILED DESCRIPTION OF THE INVENTION

The composite according to the invention has the advantage that there isstructural cooperation between the coated, shaped polycarbonate articleand the polymer, although the shaped article and the polymer undergoneither chemical nor physical bonding. Physical bonding means e.g. aparticularly firm adhesion.

Polycarbonates in the context of the present invention are bothhomopolycarbonates and copolycarbonates. The polycarbonates can belinear or branched. The homopolycarbonate based on bisphenol A(2,2-bis-(4-hydroxyphenyl)-propane) or the copolycarbonate based onbisphenol A and up to 60 mole %, based on the molar sum of bisphenols,1,1-bis-(4-hydroxyphenyl)-3,3,5-trimethylcyclohexane is preferablyemployed. The homopolycarbonate based on bisphenol A is particularlypreferably employed.

Polycarbonates in the context of the present invention are also thosearomatic polycarbonates in which up to 80 mole %, preferably from 20mole % up to 50 mole %, of the carbonates groups are replaced byaromatic dicarboxylic acid ester groups. Such polycarbonates, whichcontain both acid radicals of carbonic acid and acid radicals ofaromatic dicarboxylic acids incorporated into the molecular chain, arecalled aromatic polyester-carbonates. They are to be summarized underthe generic term of polycarbonates.

Polycarbonates can be prepared by known processes. Reference by way ofexample is made here only to Schnell, Chemistry of Physics ofPolycarbonates, Polymer Reviews, volume 9, Interscience Publishers, NewYork, London, Sydney 1964, and to D. C. Prevorsek, B. T. Debona and Y.Kesten, Corporate Research Center, Allied Chemical Corporation,Morristown, N.J. 07960, “Synthesis of Poly(ester-carbonate)copolymers”in Journal of Polymer Science, Polymer Chemistry Edition, vol. 19, 75-90(1980), and to D. Freitag, U. Grigo, P. R. Müller, N. Nouvertne, BAYER AG, “Polycarbonates” in Encyclopaedia of Polymer Science and Engineering,volume 11, 1988, second edition, 1988 pages 648-718 and finally to U.Grigo, K. Kircher and P. R. Müller, “Polycarbonate” in Becker, Braun,Kunststoff-Handbuch, volume 3/1, Polycarbonate, Polyacetale, Polyester,Celluloeester, Carl Hanser Verlag Munich, Vienna, 1992, pages 117-299.

The polycarbonates according to the invention have average molecularweights {overscore (M)}_(w) of 12,000 to 400,000 g/mole (determined bymeasuring the relative viscosity of a solution of methylene chloridehaving a concentration of 0.5 g polycarbonate per 100 ml methylenechloride at 25° C.), preferably of 18,000 to 80,000 g/mole, and inparticular 22,000 to 60,000 g/mole.

The polycarbonates according to the invention may comprise additives.

Coated in the context of the invention means that the shapedpolycarbonate article is provided with a scratch-resistant surfacecoating which is also resistant to chemicals and optionally absorbs UV,and can additionally have hydrophilic or hydrophobic properties.Preferably, more than 50% of the edge region of the shaped articleaccording to the invention of polycarbonate is coated. Particularlypreferably, more than 75% of the edge region is coated.

All coatings known to the expert which render the polycarbonatescratch-resistant such that it has a glass-like surface structure can beemployed as the surface coating. A surface coating such as is describedin WO 95/13 426 is preferably employed.

The composite according to the present invention is achieved byinjection-moulding or casting a polymer around the shaped article in theedge region. Polymers in the context of the invention include allthermoplastics, and also rubber-like polymers (rubbers), such as areemployed e.g. as a sealing composition, or also thermosetting polymers.Blends of the polymers mentioned can also be employed.

The composite according to the invention is preferably produced byinjection-moulding thermoplastics around the shaped article.

Examples of thermoplastics which may be mentioned are polystyrene,polyurethane, polyamide, polyester, polyacetal, polyacrylate,polycarbonate, polyethylene, polypropylene, polyvinyl chloride,polystyrene/acrylonitrile and copolymers based on the polymers mentionedand blends of the polymers or copolymers mentioned with another or withfurther polymers.

Rubber-like polymers in the context of the invention are e.g.polyisoprene, polychloroprene, styrerne/butadiene rubber, rubber-likeABS polymers and copolymers of ethylene and one or more of the followingcompounds: vinyl acetate, acrylic acid esters, methacrylic acid estersor propylene.

Casting resins, such as e.g. unsaturated polyesters, epoxy resincompositions, acrylates, formaldehyde resins or polyurethanes, canfurthermore also be used as polymers in the context of the invention.

Thermoplastics, rubbers and thermosetting resins which can be employedaccording to the invention are listed e.g. in Saechtling,Kunststoff-Taschenbuch, edition 26, Carl Hanser Verlag, Munich, Vienna,1995 and in Vieweg and Braun, Kunststoff-Handbuch, Carl Hanser VerlagMunich, Vienna, 1995, and in Becker, Braun, Kunststoff-Handbuch, CarlHanser Verlag Munich, Vienna, 1992.

The polymers according to the invention may comprise additives.

The composite according to the invention is preferably produced byinjection-moulding thermoplastics around the shaped article.

The shaped polycarbonate article is preferably a sheet or a film. Thesheet can be either flat or curved. Curved in the context of theinvention means that the sheet is curved such that it has a particularshape, for example as is required in automobile construction in the formof the front windscreen or rear screen, or as skylights in houseconstruction. The sheet preferably has a thickness of 1 mm to 3 cm,particularly preferably 3 mm to 10 mm. The film preferably has athickness of less than 1 mm, particularly preferably 0.25 to 1.0 mm.

In another preferred embodiment of the invention, the shaped article hasa curved surface, such as occurs in particular in optical lenses.

The shaped article preferably has, as an adhesion-promoting geometricfeature in the edge region, one or more recesses or circular or ovalbores or indentations or scallops or stamp-outs or half-stamps orcorrugations, which are enveloped by the polymer when the polymer isinjection-moulded or cast around the shaped article, so that astructurally firm connection results between the shaped article and thepolymer.

A preferred embodiment of the invention is a composite structure ofpolycarbonate based on bisphenol A, the surface of which is coated, anda thermoplastic; the production and use thereof; and products producedtherefrom.

The edge region preferably comprises less than 20% of the total surfacearea of the shaped article according to the invention of polycarbonate.It particularly preferably comprises less than 10%. Edge region is to beunderstood as e.g. the surface close to the edge of a sheet. In the caseof shaped articles which have no clear edge, such as e.g. a sphere, theedge region is an arbitrarily chosen part of the surface of the shapedarticle.

The composite according to the invention is suitable for the productionof various products. The composite according to the invention isparticularly suitable for the production of framed objects, such as e.g.slide frames.

The composite according to the invention is furthermore particularlysuitable for the production of polycarbonate window panes, either theseal or even the entire frame being attached to the coated polycarbonatepane by an injection moulding operation.

The composite according to the invention is furthermore particularlysuitable for the production of car headlamps. In this case e.g. theheadlamp lens can be formed by a shaped polycarbonate article accordingto the invention.

Another preferred use of the composite according to the invention is theproduction of picture frames, wherein the polycarbonate sheet may alsobe provided with an anti-reflex coating.

The composite according to the invention is preferably also used for theproduction of glazing for motor vehicles.

Another preferred use is the production of displays in all types ofhousings of plastic, in particular displays for computers and mobiletelephones. The matt screen of televisions can also be produced from thecomposite according to the invention.

The invention is explained below with the aid of FIGS. 1 to 3. Theseexplanations are merely by way of example and therefore do not limit theinvention.

FIG. 1 shows a coated polycarbonate film 11, 0.8 mm thick, which isprovided with 16 bores 20 (only eight (8) of which are shown) in theedge region 23. A thermoplastic (for example) is injection-mouldedaround film 11 in the edge region 23 such that a plastic element 35,e.g., a frame is formed. During injection moulding around film 11, thethermoplastic material penetrates into bores 20, so that a structurallyfirm composite 16 is formed. The number and diameter of the bores dependon the forces which act between the film and the frame, i.e., thestrength the composite is to have.

FIG. 2 shows a coated polycarbonate sheet 12, 5 mm thick, which hasindentations 26 with under cuts in the edge region 6. The indentationswere cast into sheet 12. The indentations 26 are filled with athermoplastic material when such is injection-moulded aroundpolycarbonate sheet 12, so that a structurally firm connection formsbetween the thermoplastic material and the sheet 12. This type ofcomposite is particularly suitable for a glazing.

FIG. 3 shows a section through a polycarbonate film 1. The film 1 hasindentations or scallops 2 in the edge region 29 which are incorporatedinto film 1 with a blunt tool. When a thermoplastic material isinjection-moulded around film 1, this encloses the indentations orscallops 2, and thus produces a structurally firm composite.

FIG. 4 shows a perspective view of a polycarbonate film 14 withhalf-stamps 32 in the edge region 38. A segment 3, e.g., circular, ispartly stamped out of sheet 14 and is bent outwards during stamping.When a thermoplastic material is injection-moulded around sheet 14, thisencloses the projecting, approximately circular disc 4 and thus producesa structurally firm composite.

In an embodiment of the present invention, composite structure 16 ofFIG. 1 is a window, in which case polymer element 35 is a plastic frameor a seal. In another embodiment of the present invention, compositestructure 16 of FIG. 1 may be a slide frame or a glazing for anautomobile. In a further embodiment of the present invention,polycarbonate film 11, of composite structure 16 of FIG. 1, is a displayin a plastic housing 35.

What is claimed is:
 1. A composite structure comprising: (a) a shapedpolycarbonate article having an edge region, said edge region having anadhesion-promoting geometric feature therein, said adhesion-promotinggeometric feature being selected from the group consisting of bores,indentations, scallops, stamp-outs, half-stamps and corrugations; (b) acoating on the surface of said shaped polycarbonate article; and (c) athermoplastic polymer that is one of injection-moulded and cast over theedge region of said shaped polycarbonate article, said thermoplasticpolymer enveloping said adhesion-promoting geometric feature of saidshaped polycarbonate article, the envelopment of said adhesion-promotinggeometric feature by said thermoplastic polymer providing a structurallyfirm connection between said shaped polycarbonate article (a) and saidthermoplastic polymer (c).
 2. The composite structure of claim 1 whereinsaid shaped polycarbonate article (a) is selected from flat sheet, flatfilm, curved sheet and curved film.
 3. The composite structure of claim1 wherein said coating (b) is a scratch-resistant coating.
 4. An articleprepared from the composite structure of claim
 1. 5. The compositestructure of claim 1 wherein said composite structure is one of apicture frame and a slide frame.
 6. The composite structure of claim 1wherein said composite structure is a window having one of a seal and aframe.
 7. The composite structure of claim 1 wherein said compositestructure is a glazing for a motor vehicle.
 8. The composite structureof claim 1 wherein said composite structure is a display in a plasticshousing.
 9. The composite structure of claim 1 wherein saidadhesion-promoting geometric feature is selected from bores, and saidpolymer (c) envelopes and penetrates the bores.
 10. The compositestructure of claim 1 wherein said adhesion-promoting geometric featureis selected from indentations, and said polymer (c) envelopes and fillsthe indentations.
 11. The composite structure of claim 1 wherein saidedge region of said shaped polycarbonate article (a) comprises less than20% of the total surface area of said shaped polycarbonate article (a).12. The composite structure of claim 1 wherein said edge region of saidshaped polycarbonate article (a) comprises less than 10% of the totalsurface area of said shaped polycarbonate article (a).
 13. A process forproducing a composite structure comprising: (a) providing a shapedpolycarbonate article having an edge region, said edge region having anadhesion-promoting geometric feature therein, said adhesion-promotinggeometric feature being selected from the group consisting of bores,indentations, scallops, stamp-outs, half-stamps and corrugations; (b)applying a coating over the surface of said shaped polycarbonatearticle; and (c) one of injection-moulding and casting a thermoplasticpolymer over the edge region of said shaped polycarbonate article, saidthermoplastic polymer enveloping said adhesion-promoting geometricfeature of said shaped polycarbonate article, the envelopment of saidadhesion-promoting geometric feature by said thermoplastic polymerproviding a structurally firm connection between said shapedpolycarbonate article (a) and said thermoplastic polymer (c).